1. Field of the Invention
The present invention relates to a flame retardant for treatment of wood and to flame resistant wood products treated with the same.
2. Description of the Prior Art
The inventors have previously proposed a flame retardant for treatment of wood, which comprises 3-(dialkylphosphono)propionamides and melamine resins and has a pH of not higher than 3 (JP-A-62-11792, the term "JP-A" as used herein means an "unexamined published Japanese patent application").
The flame retardant not only exhibits excellent flame retarding effects but also is capable of providing remarkable weather resistance to wood. However, the prior known flame retardant has the following drawbacks:
(1) Coated films of the ratardant shows an undesirable gloss;
(2) When the ratardant is coated heavily, e.g., at a coverage of 200 g/m.sup.2 (as a solid content) or more in order to attain a higher level of flame resistance, cracks are formed with the lapse of time or by outdoor exposure;
(3) In incombustibility test, a relatively long flame-remaining time is found after removal of heat source; and
(4) A long curing time is required when coated heavily.